--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/space.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,769 @@
+/*
+ * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "classfile/vmSymbols.hpp"
+#include "gc/serial/defNewGeneration.hpp"
+#include "gc/shared/blockOffsetTable.inline.hpp"
+#include "gc/shared/collectedHeap.inline.hpp"
+#include "gc/shared/genCollectedHeap.hpp"
+#include "gc/shared/genOopClosures.inline.hpp"
+#include "gc/shared/space.hpp"
+#include "gc/shared/space.inline.hpp"
+#include "gc/shared/spaceDecorator.hpp"
+#include "memory/universe.inline.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/java.hpp"
+#include "runtime/orderAccess.inline.hpp"
+#include "runtime/prefetch.inline.hpp"
+#include "runtime/safepoint.hpp"
+#include "utilities/align.hpp"
+#include "utilities/copy.hpp"
+#include "utilities/globalDefinitions.hpp"
+#include "utilities/macros.hpp"
+
+HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
+ HeapWord* top_obj) {
+ if (top_obj != NULL) {
+ if (_sp->block_is_obj(top_obj)) {
+ if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
+ if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
+ // An arrayOop is starting on the dirty card - since we do exact
+ // store checks for objArrays we are done.
+ } else {
+ // Otherwise, it is possible that the object starting on the dirty
+ // card spans the entire card, and that the store happened on a
+ // later card. Figure out where the object ends.
+ // Use the block_size() method of the space over which
+ // the iteration is being done. That space (e.g. CMS) may have
+ // specific requirements on object sizes which will
+ // be reflected in the block_size() method.
+ top = top_obj + oop(top_obj)->size();
+ }
+ }
+ } else {
+ top = top_obj;
+ }
+ } else {
+ assert(top == _sp->end(), "only case where top_obj == NULL");
+ }
+ return top;
+}
+
+void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
+ HeapWord* bottom,
+ HeapWord* top) {
+ // 1. Blocks may or may not be objects.
+ // 2. Even when a block_is_obj(), it may not entirely
+ // occupy the block if the block quantum is larger than
+ // the object size.
+ // We can and should try to optimize by calling the non-MemRegion
+ // version of oop_iterate() for all but the extremal objects
+ // (for which we need to call the MemRegion version of
+ // oop_iterate()) To be done post-beta XXX
+ for (; bottom < top; bottom += _sp->block_size(bottom)) {
+ // As in the case of contiguous space above, we'd like to
+ // just use the value returned by oop_iterate to increment the
+ // current pointer; unfortunately, that won't work in CMS because
+ // we'd need an interface change (it seems) to have the space
+ // "adjust the object size" (for instance pad it up to its
+ // block alignment or minimum block size restrictions. XXX
+ if (_sp->block_is_obj(bottom) &&
+ !_sp->obj_allocated_since_save_marks(oop(bottom))) {
+ oop(bottom)->oop_iterate(_cl, mr);
+ }
+ }
+}
+
+// We get called with "mr" representing the dirty region
+// that we want to process. Because of imprecise marking,
+// we may need to extend the incoming "mr" to the right,
+// and scan more. However, because we may already have
+// scanned some of that extended region, we may need to
+// trim its right-end back some so we do not scan what
+// we (or another worker thread) may already have scanned
+// or planning to scan.
+void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
+
+ // Some collectors need to do special things whenever their dirty
+ // cards are processed. For instance, CMS must remember mutator updates
+ // (i.e. dirty cards) so as to re-scan mutated objects.
+ // Such work can be piggy-backed here on dirty card scanning, so as to make
+ // it slightly more efficient than doing a complete non-destructive pre-scan
+ // of the card table.
+ MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
+ if (pCl != NULL) {
+ pCl->do_MemRegion(mr);
+ }
+
+ HeapWord* bottom = mr.start();
+ HeapWord* last = mr.last();
+ HeapWord* top = mr.end();
+ HeapWord* bottom_obj;
+ HeapWord* top_obj;
+
+ assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
+ _precision == CardTableModRefBS::Precise,
+ "Only ones we deal with for now.");
+
+ assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
+ _cl->idempotent() || _last_bottom == NULL ||
+ top <= _last_bottom,
+ "Not decreasing");
+ NOT_PRODUCT(_last_bottom = mr.start());
+
+ bottom_obj = _sp->block_start(bottom);
+ top_obj = _sp->block_start(last);
+
+ assert(bottom_obj <= bottom, "just checking");
+ assert(top_obj <= top, "just checking");
+
+ // Given what we think is the top of the memory region and
+ // the start of the object at the top, get the actual
+ // value of the top.
+ top = get_actual_top(top, top_obj);
+
+ // If the previous call did some part of this region, don't redo.
+ if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
+ _min_done != NULL &&
+ _min_done < top) {
+ top = _min_done;
+ }
+
+ // Top may have been reset, and in fact may be below bottom,
+ // e.g. the dirty card region is entirely in a now free object
+ // -- something that could happen with a concurrent sweeper.
+ bottom = MIN2(bottom, top);
+ MemRegion extended_mr = MemRegion(bottom, top);
+ assert(bottom <= top &&
+ (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
+ _min_done == NULL ||
+ top <= _min_done),
+ "overlap!");
+
+ // Walk the region if it is not empty; otherwise there is nothing to do.
+ if (!extended_mr.is_empty()) {
+ walk_mem_region(extended_mr, bottom_obj, top);
+ }
+
+ // An idempotent closure might be applied in any order, so we don't
+ // record a _min_done for it.
+ if (!_cl->idempotent()) {
+ _min_done = bottom;
+ } else {
+ assert(_min_done == _last_explicit_min_done,
+ "Don't update _min_done for idempotent cl");
+ }
+}
+
+DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
+ CardTableModRefBS::PrecisionStyle precision,
+ HeapWord* boundary,
+ bool parallel) {
+ return new DirtyCardToOopClosure(this, cl, precision, boundary);
+}
+
+HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
+ HeapWord* top_obj) {
+ if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
+ if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
+ if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
+ // An arrayOop is starting on the dirty card - since we do exact
+ // store checks for objArrays we are done.
+ } else {
+ // Otherwise, it is possible that the object starting on the dirty
+ // card spans the entire card, and that the store happened on a
+ // later card. Figure out where the object ends.
+ assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
+ "Block size and object size mismatch");
+ top = top_obj + oop(top_obj)->size();
+ }
+ }
+ } else {
+ top = (_sp->toContiguousSpace())->top();
+ }
+ return top;
+}
+
+void FilteringDCTOC::walk_mem_region(MemRegion mr,
+ HeapWord* bottom,
+ HeapWord* top) {
+ // Note that this assumption won't hold if we have a concurrent
+ // collector in this space, which may have freed up objects after
+ // they were dirtied and before the stop-the-world GC that is
+ // examining cards here.
+ assert(bottom < top, "ought to be at least one obj on a dirty card.");
+
+ if (_boundary != NULL) {
+ // We have a boundary outside of which we don't want to look
+ // at objects, so create a filtering closure around the
+ // oop closure before walking the region.
+ FilteringClosure filter(_boundary, _cl);
+ walk_mem_region_with_cl(mr, bottom, top, &filter);
+ } else {
+ // No boundary, simply walk the heap with the oop closure.
+ walk_mem_region_with_cl(mr, bottom, top, _cl);
+ }
+
+}
+
+// We must replicate this so that the static type of "FilteringClosure"
+// (see above) is apparent at the oop_iterate calls.
+#define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
+void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
+ HeapWord* bottom, \
+ HeapWord* top, \
+ ClosureType* cl) { \
+ bottom += oop(bottom)->oop_iterate_size(cl, mr); \
+ if (bottom < top) { \
+ HeapWord* next_obj = bottom + oop(bottom)->size(); \
+ while (next_obj < top) { \
+ /* Bottom lies entirely below top, so we can call the */ \
+ /* non-memRegion version of oop_iterate below. */ \
+ oop(bottom)->oop_iterate(cl); \
+ bottom = next_obj; \
+ next_obj = bottom + oop(bottom)->size(); \
+ } \
+ /* Last object. */ \
+ oop(bottom)->oop_iterate(cl, mr); \
+ } \
+}
+
+// (There are only two of these, rather than N, because the split is due
+// only to the introduction of the FilteringClosure, a local part of the
+// impl of this abstraction.)
+ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
+ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
+
+DirtyCardToOopClosure*
+ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
+ CardTableModRefBS::PrecisionStyle precision,
+ HeapWord* boundary,
+ bool parallel) {
+ return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
+}
+
+void Space::initialize(MemRegion mr,
+ bool clear_space,
+ bool mangle_space) {
+ HeapWord* bottom = mr.start();
+ HeapWord* end = mr.end();
+ assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
+ "invalid space boundaries");
+ set_bottom(bottom);
+ set_end(end);
+ if (clear_space) clear(mangle_space);
+}
+
+void Space::clear(bool mangle_space) {
+ if (ZapUnusedHeapArea && mangle_space) {
+ mangle_unused_area();
+ }
+}
+
+ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
+ _concurrent_iteration_safe_limit(NULL) {
+ _mangler = new GenSpaceMangler(this);
+}
+
+ContiguousSpace::~ContiguousSpace() {
+ delete _mangler;
+}
+
+void ContiguousSpace::initialize(MemRegion mr,
+ bool clear_space,
+ bool mangle_space)
+{
+ CompactibleSpace::initialize(mr, clear_space, mangle_space);
+ set_concurrent_iteration_safe_limit(top());
+}
+
+void ContiguousSpace::clear(bool mangle_space) {
+ set_top(bottom());
+ set_saved_mark();
+ CompactibleSpace::clear(mangle_space);
+}
+
+bool ContiguousSpace::is_free_block(const HeapWord* p) const {
+ return p >= _top;
+}
+
+void OffsetTableContigSpace::clear(bool mangle_space) {
+ ContiguousSpace::clear(mangle_space);
+ _offsets.initialize_threshold();
+}
+
+void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
+ Space::set_bottom(new_bottom);
+ _offsets.set_bottom(new_bottom);
+}
+
+void OffsetTableContigSpace::set_end(HeapWord* new_end) {
+ // Space should not advertise an increase in size
+ // until after the underlying offset table has been enlarged.
+ _offsets.resize(pointer_delta(new_end, bottom()));
+ Space::set_end(new_end);
+}
+
+#ifndef PRODUCT
+
+void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
+ mangler()->set_top_for_allocations(v);
+}
+void ContiguousSpace::set_top_for_allocations() {
+ mangler()->set_top_for_allocations(top());
+}
+void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
+ mangler()->check_mangled_unused_area(limit);
+}
+
+void ContiguousSpace::check_mangled_unused_area_complete() {
+ mangler()->check_mangled_unused_area_complete();
+}
+
+// Mangled only the unused space that has not previously
+// been mangled and that has not been allocated since being
+// mangled.
+void ContiguousSpace::mangle_unused_area() {
+ mangler()->mangle_unused_area();
+}
+void ContiguousSpace::mangle_unused_area_complete() {
+ mangler()->mangle_unused_area_complete();
+}
+#endif // NOT_PRODUCT
+
+void CompactibleSpace::initialize(MemRegion mr,
+ bool clear_space,
+ bool mangle_space) {
+ Space::initialize(mr, clear_space, mangle_space);
+ set_compaction_top(bottom());
+ _next_compaction_space = NULL;
+}
+
+void CompactibleSpace::clear(bool mangle_space) {
+ Space::clear(mangle_space);
+ _compaction_top = bottom();
+}
+
+HeapWord* CompactibleSpace::forward(oop q, size_t size,
+ CompactPoint* cp, HeapWord* compact_top) {
+ // q is alive
+ // First check if we should switch compaction space
+ assert(this == cp->space, "'this' should be current compaction space.");
+ size_t compaction_max_size = pointer_delta(end(), compact_top);
+ while (size > compaction_max_size) {
+ // switch to next compaction space
+ cp->space->set_compaction_top(compact_top);
+ cp->space = cp->space->next_compaction_space();
+ if (cp->space == NULL) {
+ cp->gen = GenCollectedHeap::heap()->young_gen();
+ assert(cp->gen != NULL, "compaction must succeed");
+ cp->space = cp->gen->first_compaction_space();
+ assert(cp->space != NULL, "generation must have a first compaction space");
+ }
+ compact_top = cp->space->bottom();
+ cp->space->set_compaction_top(compact_top);
+ cp->threshold = cp->space->initialize_threshold();
+ compaction_max_size = pointer_delta(cp->space->end(), compact_top);
+ }
+
+ // store the forwarding pointer into the mark word
+ if ((HeapWord*)q != compact_top) {
+ q->forward_to(oop(compact_top));
+ assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
+ } else {
+ // if the object isn't moving we can just set the mark to the default
+ // mark and handle it specially later on.
+ q->init_mark();
+ assert(q->forwardee() == NULL, "should be forwarded to NULL");
+ }
+
+ compact_top += size;
+
+ // we need to update the offset table so that the beginnings of objects can be
+ // found during scavenge. Note that we are updating the offset table based on
+ // where the object will be once the compaction phase finishes.
+ if (compact_top > cp->threshold)
+ cp->threshold =
+ cp->space->cross_threshold(compact_top - size, compact_top);
+ return compact_top;
+}
+
+void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
+ scan_and_forward(this, cp);
+}
+
+void CompactibleSpace::adjust_pointers() {
+ // Check first is there is any work to do.
+ if (used() == 0) {
+ return; // Nothing to do.
+ }
+
+ scan_and_adjust_pointers(this);
+}
+
+void CompactibleSpace::compact() {
+ scan_and_compact(this);
+}
+
+void Space::print_short() const { print_short_on(tty); }
+
+void Space::print_short_on(outputStream* st) const {
+ st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
+ (int) ((double) used() * 100 / capacity()));
+}
+
+void Space::print() const { print_on(tty); }
+
+void Space::print_on(outputStream* st) const {
+ print_short_on(st);
+ st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
+ p2i(bottom()), p2i(end()));
+}
+
+void ContiguousSpace::print_on(outputStream* st) const {
+ print_short_on(st);
+ st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
+ p2i(bottom()), p2i(top()), p2i(end()));
+}
+
+void OffsetTableContigSpace::print_on(outputStream* st) const {
+ print_short_on(st);
+ st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
+ INTPTR_FORMAT ", " INTPTR_FORMAT ")",
+ p2i(bottom()), p2i(top()), p2i(_offsets.threshold()), p2i(end()));
+}
+
+void ContiguousSpace::verify() const {
+ HeapWord* p = bottom();
+ HeapWord* t = top();
+ HeapWord* prev_p = NULL;
+ while (p < t) {
+ oop(p)->verify();
+ prev_p = p;
+ p += oop(p)->size();
+ }
+ guarantee(p == top(), "end of last object must match end of space");
+ if (top() != end()) {
+ guarantee(top() == block_start_const(end()-1) &&
+ top() == block_start_const(top()),
+ "top should be start of unallocated block, if it exists");
+ }
+}
+
+void Space::oop_iterate(ExtendedOopClosure* blk) {
+ ObjectToOopClosure blk2(blk);
+ object_iterate(&blk2);
+}
+
+bool Space::obj_is_alive(const HeapWord* p) const {
+ assert (block_is_obj(p), "The address should point to an object");
+ return true;
+}
+
+#if INCLUDE_ALL_GCS
+#define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
+ \
+ void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
+ HeapWord* obj_addr = mr.start(); \
+ HeapWord* t = mr.end(); \
+ while (obj_addr < t) { \
+ assert(oopDesc::is_oop(oop(obj_addr)), "Should be an oop"); \
+ obj_addr += oop(obj_addr)->oop_iterate_size(blk); \
+ } \
+ }
+
+ ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
+
+#undef ContigSpace_PAR_OOP_ITERATE_DEFN
+#endif // INCLUDE_ALL_GCS
+
+void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
+ if (is_empty()) return;
+ HeapWord* obj_addr = bottom();
+ HeapWord* t = top();
+ // Could call objects iterate, but this is easier.
+ while (obj_addr < t) {
+ obj_addr += oop(obj_addr)->oop_iterate_size(blk);
+ }
+}
+
+void ContiguousSpace::object_iterate(ObjectClosure* blk) {
+ if (is_empty()) return;
+ object_iterate_from(bottom(), blk);
+}
+
+// For a ContiguousSpace object_iterate() and safe_object_iterate()
+// are the same.
+void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
+ object_iterate(blk);
+}
+
+void ContiguousSpace::object_iterate_from(HeapWord* mark, ObjectClosure* blk) {
+ while (mark < top()) {
+ blk->do_object(oop(mark));
+ mark += oop(mark)->size();
+ }
+}
+
+HeapWord*
+ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
+ HeapWord * limit = concurrent_iteration_safe_limit();
+ assert(limit <= top(), "sanity check");
+ for (HeapWord* p = bottom(); p < limit;) {
+ size_t size = blk->do_object_careful(oop(p));
+ if (size == 0) {
+ return p; // failed at p
+ } else {
+ p += size;
+ }
+ }
+ return NULL; // all done
+}
+
+#define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
+ \
+void ContiguousSpace:: \
+oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
+ HeapWord* t; \
+ HeapWord* p = saved_mark_word(); \
+ assert(p != NULL, "expected saved mark"); \
+ \
+ const intx interval = PrefetchScanIntervalInBytes; \
+ do { \
+ t = top(); \
+ while (p < t) { \
+ Prefetch::write(p, interval); \
+ debug_only(HeapWord* prev = p); \
+ oop m = oop(p); \
+ p += m->oop_iterate_size(blk); \
+ } \
+ } while (t < top()); \
+ \
+ set_saved_mark_word(p); \
+}
+
+ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
+
+#undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
+
+// Very general, slow implementation.
+HeapWord* ContiguousSpace::block_start_const(const void* p) const {
+ assert(MemRegion(bottom(), end()).contains(p),
+ "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
+ p2i(p), p2i(bottom()), p2i(end()));
+ if (p >= top()) {
+ return top();
+ } else {
+ HeapWord* last = bottom();
+ HeapWord* cur = last;
+ while (cur <= p) {
+ last = cur;
+ cur += oop(cur)->size();
+ }
+ assert(oopDesc::is_oop(oop(last)), PTR_FORMAT " should be an object start", p2i(last));
+ return last;
+ }
+}
+
+size_t ContiguousSpace::block_size(const HeapWord* p) const {
+ assert(MemRegion(bottom(), end()).contains(p),
+ "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
+ p2i(p), p2i(bottom()), p2i(end()));
+ HeapWord* current_top = top();
+ assert(p <= current_top,
+ "p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
+ p2i(p), p2i(current_top));
+ assert(p == current_top || oopDesc::is_oop(oop(p)),
+ "p (" PTR_FORMAT ") is not a block start - "
+ "current_top: " PTR_FORMAT ", is_oop: %s",
+ p2i(p), p2i(current_top), BOOL_TO_STR(oopDesc::is_oop(oop(p))));
+ if (p < current_top) {
+ return oop(p)->size();
+ } else {
+ assert(p == current_top, "just checking");
+ return pointer_delta(end(), (HeapWord*) p);
+ }
+}
+
+// This version requires locking.
+inline HeapWord* ContiguousSpace::allocate_impl(size_t size) {
+ assert(Heap_lock->owned_by_self() ||
+ (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()),
+ "not locked");
+ HeapWord* obj = top();
+ if (pointer_delta(end(), obj) >= size) {
+ HeapWord* new_top = obj + size;
+ set_top(new_top);
+ assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
+ return obj;
+ } else {
+ return NULL;
+ }
+}
+
+// This version is lock-free.
+inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size) {
+ do {
+ HeapWord* obj = top();
+ if (pointer_delta(end(), obj) >= size) {
+ HeapWord* new_top = obj + size;
+ HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
+ // result can be one of two:
+ // the old top value: the exchange succeeded
+ // otherwise: the new value of the top is returned.
+ if (result == obj) {
+ assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
+ return obj;
+ }
+ } else {
+ return NULL;
+ }
+ } while (true);
+}
+
+HeapWord* ContiguousSpace::allocate_aligned(size_t size) {
+ assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked");
+ HeapWord* end_value = end();
+
+ HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes);
+ if (obj == NULL) {
+ return NULL;
+ }
+
+ if (pointer_delta(end_value, obj) >= size) {
+ HeapWord* new_top = obj + size;
+ set_top(new_top);
+ assert(::is_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top),
+ "checking alignment");
+ return obj;
+ } else {
+ set_top(obj);
+ return NULL;
+ }
+}
+
+// Requires locking.
+HeapWord* ContiguousSpace::allocate(size_t size) {
+ return allocate_impl(size);
+}
+
+// Lock-free.
+HeapWord* ContiguousSpace::par_allocate(size_t size) {
+ return par_allocate_impl(size);
+}
+
+void ContiguousSpace::allocate_temporary_filler(int factor) {
+ // allocate temporary type array decreasing free size with factor 'factor'
+ assert(factor >= 0, "just checking");
+ size_t size = pointer_delta(end(), top());
+
+ // if space is full, return
+ if (size == 0) return;
+
+ if (factor > 0) {
+ size -= size/factor;
+ }
+ size = align_object_size(size);
+
+ const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
+ if (size >= align_object_size(array_header_size)) {
+ size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
+ // allocate uninitialized int array
+ typeArrayOop t = (typeArrayOop) allocate(size);
+ assert(t != NULL, "allocation should succeed");
+ t->set_mark(markOopDesc::prototype());
+ t->set_klass(Universe::intArrayKlassObj());
+ t->set_length((int)length);
+ } else {
+ assert(size == CollectedHeap::min_fill_size(),
+ "size for smallest fake object doesn't match");
+ instanceOop obj = (instanceOop) allocate(size);
+ obj->set_mark(markOopDesc::prototype());
+ obj->set_klass_gap(0);
+ obj->set_klass(SystemDictionary::Object_klass());
+ }
+}
+
+HeapWord* OffsetTableContigSpace::initialize_threshold() {
+ return _offsets.initialize_threshold();
+}
+
+HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
+ _offsets.alloc_block(start, end);
+ return _offsets.threshold();
+}
+
+OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
+ MemRegion mr) :
+ _offsets(sharedOffsetArray, mr),
+ _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
+{
+ _offsets.set_contig_space(this);
+ initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
+}
+
+#define OBJ_SAMPLE_INTERVAL 0
+#define BLOCK_SAMPLE_INTERVAL 100
+
+void OffsetTableContigSpace::verify() const {
+ HeapWord* p = bottom();
+ HeapWord* prev_p = NULL;
+ int objs = 0;
+ int blocks = 0;
+
+ if (VerifyObjectStartArray) {
+ _offsets.verify();
+ }
+
+ while (p < top()) {
+ size_t size = oop(p)->size();
+ // For a sampling of objects in the space, find it using the
+ // block offset table.
+ if (blocks == BLOCK_SAMPLE_INTERVAL) {
+ guarantee(p == block_start_const(p + (size/2)),
+ "check offset computation");
+ blocks = 0;
+ } else {
+ blocks++;
+ }
+
+ if (objs == OBJ_SAMPLE_INTERVAL) {
+ oop(p)->verify();
+ objs = 0;
+ } else {
+ objs++;
+ }
+ prev_p = p;
+ p += size;
+ }
+ guarantee(p == top(), "end of last object must match end of space");
+}
+
+
+size_t TenuredSpace::allowed_dead_ratio() const {
+ return MarkSweepDeadRatio;
+}